feat: add various detector.

- add endian and compiler detector, and modify os detector.
- now we use CMake to add detector-used macro, instead of using some C++ features to detect them.
- change Windows environment detection according to the change of os detector.

doc/src/library_macros.dox

@@ -73,7 +73,7 @@ Assume \c blabla() function is Windows specific.
 We have following example code:
 
 \code
-#if YYCC_OS == YYCC_OS_WINDOWS
+#if defined(YYCC_OS_WINDOWS)
 blabla();
 #endif
 \endcode

doc/src/win_import.dox

@@ -11,7 +11,7 @@ Due to legacy reason, Windows defines various things which are not compatible wi
 YYCC has a way to solve the issue introduced above.
 
 \code
-#if YYCC_OS == YYCC_OS_WINDOWS
+#if defined(YYCC_OS_WINDOWS)
 #include <WinImportPrefix.hpp>
 #include <Windows.h>
 #include "other_header_depend_on_windows.h"